Monitoring of an infiltration experiment using the self-potential method

[ 1] An infiltration test was performed from a ditch with the purpose of monitoring the evolution of the piezometric levels using self-potential measurements made at the ground surface. We used a set of 18 piezometers and a network of 41 nonpolarizable (Pb/PbCl2) electrodes. The variations of the self-potential signals are linearly correlated to the piezometric level changes with an apparent voltage coupling coefficient of - 5.5 +/- 0.9 mV m(-1). We measured, independently of this infiltration test, the three material properties entering the macroscopic field equations. They are the resistivity distribution of the soil, its mean hydraulic conductivity, and its intrinsic streaming potential coupling coefficient ( - 5.8 +/- 1.1 mV m(-1)). Then, we modeled numerically the infiltration test and the associated self-potential signals using a two-dimensional finite difference code. The numerical model reproduces fairly well the observed results. This investigation demonstrates the effectiveness of the self-potential method in field conditions to monitor small variations (< 0.60 m) of the water table. It offers for the first time a test of the electrokinetic theory in the field with independent evaluation of the material properties entering the field equations.